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Fatbike Tubeless

I’ve thought and thought about it, and finally made the leap to tubeless fatbiking.

In the past, I’ve run Surly tubes, exclusively…with a multitude of tires, predominantly spending time with Big Fat Larrys and Husker Düs. Current setup is holey Rolling Darryl’s, the lightweight, high TPI Huskers, Surly tube, Surly rim strip. I’ve been pretty pleased…but I’m all about the reduction of rolling weight for the fatbike. (Really, for all bikes). So I decided to try tubeless.

There are 3 basic tubeless systems:

1) Taped Tubeless: Take a fatbike rim and use heavy duty tape (most use Gorilla tape) to make the rim airtight. Then, insert a tubeless valve stem (a Stans, if you can find it). Insert a couple cups of Stans sealant, and inflate. This is the favorite of many riders–including Matt Gersib, whose recommendations I trust a great deal. However, if you look on MTBR and other fatbike sites, you’ll see that most people who have problems with tubeless have problems with this setup. You’re trying to get a non-tubeless tire to seal perfectly on a non-tubeless bead. In my mind, while I understand the intrinsic appeal of this setup, I couldn’t bring myself to do it.

2) Gonzo Tubeless: I’m going to make this the category of all other tubeless. This includes guys who use glue or epoxy to bond holes in the rims shut, who weld valve stems in, etc. I’ll pass.

3) Ghetto Tubeless: Take a standard bike innertube, cut it lengthwise, stretch over rim, mount tire so that tube is between bead and tire, inflate. More details below. This is the option I went with, after much research and consideration.

Why Ghetto Instead of Taped?

Taped would save another 50-100 grams, no doubt. That said, in my mind, the Ghetto seems a bit more reliable. The rubber innertube helps ensure a better seal between tire and rim, and provides more friction at the tire/rim interface, hopefully preventing blowouts, burps, etc. I was also hopeful that it would be easier to mount up and inflate, and more burp-resistant.

I dismounted everything, except for the rim strip. I then procured some closed cell foam, to use under the tube. I got mine at Lowes…3.5″ wide and 50′ long. Should be enough to do 3-4 bikes. Here’s the exact product I used:

I cut a strip that was a little longer than I needed…

And then cut it down to width. I cut about 3/4″ off of the width–leaving a gap on both sides at the bead.

Again, this is closed-cell foam, so it shouldn’t absorb any water or crud. The hole you see is for the valve stem. With the scale ‘tare-d’ with a bead tool on it, I weighed the foam at 10 grams.

For tubes, I ended up settling on 24×2.1-2.3″ Qtubes with removable valve stems. Here is the exact part:

If you look at the tube, it has a seam that runs down the outside of the tube, opposite the valve stem. Take a pair of sharp scissors and cut down that seam, all the way around the tire. You’ll end up with this:

Insert the valve stem in the appropriate hole on the wheel, and stretch the tube around the rim.

The inside of the tube is powdered, so it doesn’t chafe/rub. Take a wet rag and wipe that powder off, so you can get a good seal.

You’ll end up with the tube hanging over a little less than 1/2″ on both sides of the rim.

(So it’s rim strip, foam, cut-tube).

Then, mount one side of the tire on the rim (should go on by hand). Dump some Stans in (I used 3 cups, but 2 should suffice). Mount the 2nd side of the tire on the rim. This was a little tight, but went on easily with a bead lever.

Make sure you have a nut on the valve stem before trying to inflate. This was the moment of truth. Since the valvestems are removeable, you could pull them out to get more air into the tire, more quickly. I’ve also seen many people use a ratchet strap or other device around the tire, to squeeze it down onto the bead more tightly. However, as I looked at hte tire on the rim, with the foam, the tire looked pretty snug. I decided to give it a go as-is. No lubricants, no soapy water, valve core in, no straps. The lovely Mrs. did the filming:

As you can see, no drama. The bead seated fully at 20psi. I pumped them up to 25 and left them sit. I then did the “Stans’ Shake, Rattle and Roll” routine to move the sealant all over inside the tire and get any bubbles or holes…to my surprise, there were none. It looks like the tire sealed fully without any sealant. No bubbling or squishing. It really was that easy. I think the foam helped a great deal (just one layer), as it pushed the tube-strip out against the tire and made seating the bead very easy.

The ‘after weight’?

My Surly tubes weighed in at 555 and 560 grams. The Q-tubes weighed in at about 180 grams. Even with the 10 grams of foam and some sealant, I dropped 350 grams, front and rear…or about 1.5 pounds of rotating mass. (And the q-tube is closer to the center of the wheel, as compared to an inflated Surly tube, which should exaggerate the weight savings effect based on the centripetal force–right BPaul?) I could drop a little more if I washed the mud off of my tires…

Even if there is no benefit in traction or inflation (and I’m guessing that there will be benefits in those departments, based on previous experience with Tubeless), the loss of 1.5 pounds of rolling weight is HUGE on a fatbike. HUGE.

When I cut the tubes down, I did not narrow them. I have not cut them down post-install, either. They do look a little ghetto:

But it makes it very, very easy to get the rim strip centered and get the tire on and off easily. I have absolute confidence that I could remount and seal one of these tires on a ride, with just a CO2 cartridge (and pump it up with a handpump), and the little flap of rubber makes me confident that I could do it with numb fingers, in the snow. Hopefully, I won’t have to…but that’s my logic in leaving the tube as-is, right now. You could probably drop another 10-20 grams/wheel if you did cut down the rubber.

Ride experience is limited to driveway time right now…but I’ll update in the coming weeks. They held air overnight, and didn’t lose a single PSI. I think this is about the best weight-reduction fatbike project around, right now…dollar for dollar, we’re talking about a $20 investment for a 1.5 pound weight reduction…in rolling weight.

Great post! I have enjoyed your posts with the attention to detail and interesting subject manner for a few months now. Wondering if you just carried a tube for a bail out and cut down the tube used for sealing the tire would be an option to the overlapping rubber.

It definitely could be trimmed down tighter…or you could use a skinnier tube. As long as it gets to the bead/tire seat, you should be fine. Carrying a tube for bailout on long rides is definitely the way to go…it would be easy enough to use a tube in an emergency. My A/R tendencies will eventually get the best of me and I’ll trim it. For now, we’re still in test mode.

Neat – I would love to hear how it works for you at low pressures, like 5-8psi. Do the Rolling Darryl have much of a bead lock? Seems like this method would not let the bead lock “grip” the tire all that firmly.. Anyway, thanks for posting, looking forward to hearing how well it works for you.

Neat. I saw some Austrailan guys do this a few months ago on YouTube. What’s the reason for the foam?
“Dump some Stans in (I used 3 cups, but 2 should suffice).” Surely you don’t mean two or three 8 floz cups?

Foam: With the ghetto tubeless, the foam goes under the split tube, and helps push the tube up towards the tire’s bead. This makes it much easier to seat the bead. You don’t have to have an air compressor and a big burst of air…the foam basically seals the tire against the rim while you’re pumping it up. And at 10 grams of weight, it makes it much easier to reseat in the field, as well.

By cups, I meant the little Stans cups (the little red cup that comes with a bottle of Stans sealant). The little cup is 2 ounces…so I used about 6 ounces. 4 ounces would be more than enough, in retrospect.

I used the same method, sill foam and all. After a while the sill foam remains compressed, so it’s only good for seating once. When changing tires I have to replace the foam with fresh stuff, but it’s not a huge deal. Neoprene would have less “memory”, but would weigh more. If I’m going far away, I carry a tube for bail out.

People have asked about low pressure performance: I’ve gone down to 3 psi according to two gauges, sadly neither have given reliable readings below that. I believe I’m not exaggerating to claim I’ve gone down to 1-2 psi. At that point I could nudge the rim to hit the ground and I only weigh 71 kg (156 lbs). No burps and no rotational slips between the tire and rim. Absolutely zero problems!

I’ve done 3psi as well, running Husker Dus. I’ve run pressures below that (again, immeasurable), and peeled off the rear bead once in a very uneventful burp. It reseated on the trail with a CO2 and 0 drama.

Thanks for the info. I picked up the foam from Lowes and the Stans no tube from my LBS. I had to order the inner tubes online as my LBS didnt have a tube with a removable valve. Once the tubes comes I going tubeless. Thanks for the assist.

Nice write up. I’m trying to figure out which tubes to order to use for my rolling daryl rims. It’s either the schwalbe av10d (2.5-3.0″) or schwalbe sv10(?) (1.5-2.5″). I’d normally go for presta, but I’m happy to go schrader if they fit the valve hole. Any tips?

Out of those two, I’d go Schwalbe, for the extra width. I’m concerned that the 1.5-2.5 may not be wide enough…and you can always trim it down! Presta will fit without modification–you’d have to drill to go Schrader.

I’ve converted two standard 26″ MTB’s to ghetto tubeless and will do my yet-to-be-built fatbike within the next couple of weeks, using this blog post as my inspiration. I have this question that pertains to all of them: After trimming the excess rubber flap past the rim bead, what will you do upon the situation of an eventual burp or flat or tire change?
The rubber “rimstrip” will not overhang the rim bead anymore and will likely just bunch up in the bead seat. Do you replace the split tube every time and re-trim it?

I haven’t had a burp happen in the field, even running 2-3psi…so field conditions may be different.

In the garage, I haven’t had any problem removing and remounting tires, using the same ‘trimmed’ tube. You do need to be a bit picky about getting it even, but otherwise, it works pretty slick. The tube gets a bit worn into place, and thus goes back pretty easily.

I just finished mounting mine up tonight. Last weekend, I tried doing it without the foam strip and they wouldn’t seat at all. It didn’t help that the temperatures were in the teens, rendering both rubber surfaces hard and seal-resistant. I tried soapy water, but that just froze on the tire. Now with temps in the 30’s, I added the foam strip and just as you reported, they sealed up on the first try without any soapy water or drama of any kind. Thanks for the great advice.

On my first go-around with this, I trimmed the split tube after everything was sealed up. That was OK until I tried to re-mount it many months later with new sealant and possibly new foam (I can’t remember.) It didn’t work at all, so I split a new tube and it was flawless. From that, I’ve decided to leave the extra sticking out on future installs.

You can do this without the foam. You’ll need an air compressor and a spare Surly tube. Remove the valve cores on both the uncut and cut tubes to get more in air in faster.
1 – Lay everything up as described above (minus the foam)
2 – Stuff an uncut Surly tube in the tire as well. The valve stem will be sticking out the side of the wheel between the tire and rim (don’t sweat it – it’s just temporary!)
3 – Inflate the uncut tube enough to seat the tire beads.
4 – Break the bead on one side of the wheel only – remove uncut tube – without breaking bead on opposite tire.
5 – Position wheel on a bucket, seated bead side up. Inflate and seat the bead on the opposite side.

Thanks for this. I tried to do the taped rim method, but could not get the bead to seat. This made a huge difference. I am using the Panaracer Fat B Nimble on Weinman 80mm rims and tire is very loose. I did have to use a ratchet strap to get the tire to inflate. On the first one I did it without Stans to get the bead to seat, but once I let the air out the bead came off. So on the second one I just put the Stans in, put the valve core back in and inflated. I will say that once inflated, there was zero air leakage even before doing the Stans shake, so this is a very good seal. I’d bet you could probably do this without any sealant, but I don’t think I would risk it.

I’m glad to hear it worked. The gorilla tape method works for some, but honestly, I think the split rim is more reliable and easier to do, without a weight penalty (and with an easier conversion back to tubed, at any time).